The 3D comprehension of anatomic and computed objects in medical images, presented using shaded display, can be increased by attention to light sources, surface textures, and transparency. Increased 3D cues are provided by real-time interactive modification of viewpoint, object selection, transparency, and clipping planes. Methods for achieving these increases in comprehension will be presented. In particular, the following will be described, with applications from diagnostic CT and MRI and radiotherapy treatment planning: 1) A set of workstation-based tools, using heuristic and interactive approaches, for defining object contours, connecting them into objects, and tiling their surfaces. 2) A renderer that provides more rapid computation of many different presentations of the same view of a scene by keeping a large intermediate file of geometric information about a particular view. Choices of objects to be displayed, and for each object, its color, specularity, and transparency, can be deferred until, and changed after, all the geometric computations. 3) The usefulness of the Tektronix stereo polarizing plate and the kinetic depth effect for adding to the 3D comprehension of objects. 4) The custom-built graphics engine, Pixel-planes, and its use in providing, all in near real time, object selection, variation in object transparency levels, variation in viewpoint, and specification of clipping planes. Also described will be the ability of Pixel-planes to present oblique grey-scale image slices superimposed on the clipping planes as the clipping plane is interactively moved.

Henry Fuchs, University of North Carolina at Chapel Hill (United States)Stephen M. Pizer, University of North Carolina at Chapel Hill (United States)Jeffrey L. Creasy, University of North Carolina at Chapel Hill (United States)

Jordan B. Renner, University of North Carolina at Chapel Hill (United States)Julian G. Rosenman, University of North Carolina at Chapel Hill (United States)